1. Technical Field
The present invention relates to a touch screen device.
2. Description of the Related Art
With the continuous development in the electronic technology and the information technology fields, the relative importance of electronic devices is constantly increasing in everyday life, including work environment. In particular, as electronic technology continuously develops, personal computers, portable transmitters etc. process texts and graphics, using a variety of input devices, such as a keyboard, a mouse, a digitizer, etc. These input devices, however, have been developed in consideration of the expanding usage of personal computers, such that they are difficult to be applied to portable devices that are recently reduced in size and thickness. Therefore, touch screens are on the rise as an input device appropriate for the portable devices.
Touch screens, devices generally installed in display devices to detect positions on the screen touched by a user and control electronic devices, using information on the detected contact position as input information, in addition to controlling the screen of the display, have various advantages of being simply operated with little malfunction in a small space, while being very compatible with IT devices.
Meanwhile, with the development of the mobile communication technology, a need exists for a larger display screen in portable devices having a limited size, such that a display device using a touch screen has become the main focus. The touch screen combines a screen and coordinate input units, thereby saving space as compared to a key input scheme according to the prior art. Therefore, a display device recently developed uses a display adopting a touch screen in order to more improve a screen size and user convenience.
FIG. 1 is a cross-sectional view of a resistive touch screen device 10 according to the prior art. Hereinafter, the resistive touch screen device 10 according to the prior art will be described with reference to the figure.
As shown in FIG. 1, the resistive touch screen device 10 according to the prior art includes two sheets of transparent substrates 12, indium tin oxide (ITO) electrodes 13, a touch screen 11 including a first double-sided adhesive tape (DAT) 14, a display 15, and a second double-sided adhesive tape 16.
Herein, the ITO electrodes 13 are formed on the respective transparent substrates 12, wherein the ITO electrodes 13 are connected to the electrodes 17 to be applied with voltage. Further, the outer sides between the two sheets of transparent substrates 12 are bonded by the first double-sided adhesive layer 14 and dot spacers 18 are formed on the inner lower ITO electrode 13b between the transparent substrates 12. In addition, the display 15 is bonded to the lower transparent substrate 120b by the second double-sided adhesive tape 16, wherein the second double-sided adhesive tape 16 is formed on the outer sides between the lower transparent substrate 12b and the display 15.
Meanwhile, when a user applies pressure to the upper transparent substrate 12a so as to input an object, the upper transparent substrate 12a and the upper ITO electrode 13a are bent to face the lower transparent substrate 12b and resistance varied while the upper ITO electrode 13a are in contact with the lower ITO electrode 13b are sensed, thereby achieving coordinates of the input positions.
However, in the resistive touch screen device 10 according to the prior art, the second double-sided adhesive tape 16 is formed on the outer sides between the touch screen 11 and the display 15 so that an air layer 19 is formed on inner sides between the touch screen 11 and the display 15. Therefore, an image displayed from the lower display 15 is not definitively transmitted to a user. In other words, transmittance of the image is degraded and optical path difference is generated due to the air layer 19, such that Newton's rings or the like occurs.
In addition, the touch screen device 10 has at least four junction interfaces exposed to the outside, which are relatively numerous, such that moisture, oil, or the like is infiltrated into the inside of the touch screen device 10. More specifically, the junction interface is formed at fours areas, which are between the upper transparent substrate 12a and the first double-sided adhesive tape 14, between the first double-sided adhesive tape 14 and the lower transparent substrate 12b, between the lower transparent substrate 12b and the second double-sided adhesive tape 16, and between the second double-sided adhesive tape 16 and the display 15. The junction interface is relatively highly likely to be infiltrated with moisture, oil or the like, such that the touch screen device 10 is more frequently damaged due to the infiltrated moisture, oil or the like.